Wire stripping apparatus



June 27, 1950 M. CARPENTER ETAL 2,513,252

WIRE STRIPPING APPARATUS 2 Sheets-Sheet l Lou/s M. Cmpenfer Run/o/p/r 6. fioesch INVen TORS A TrOR/VEY Filed NOV. 6, 1945 .Jmme 27, 11950 L. M. CARPENTER ETAL WIRE STRIPPING APPARATUS 2 Sheets-Sheet 2 Lou/s M. Carpenter Filed Nov. 6, 1945 A TTORNEY Patented June 27, 1950 WIRE STRIPPING APPARATUS Louis M. Carpenter and Rudolph G. Roesch,

Syracuse, N. Y., assignors to The'Era'ser Company, Inc., Syracuse, N. Y., a corporation of New York Application November 6, 1945, Serial No. 626,998

14 Claims. 1

The invention relates to an improved means for removing coatings and coverings from wire and, more particularly, to an improved means for and method of removing insulating coverings, and insulating coating filmssuch as socalled enamel films, from electrical wire, including-especially wire of small gage generally known as resistance wire or magnet wire. Coating films used vary widely as to hardness andtoughness and as to. the tenacity with which they. adhere to the wire. Such wires with insulating coverings, or with adherent insulating coatings or films, are widely used in radio and radar equipment, magnet coils, rheostats, potentiometers, electric controls, measuring instruments, etc.

Electrical wire of small gage with an insulating covering or coating has long been used and, in recent years, the demand for such insulated wire has vastly increased along with a demandfo wire of. smaller and smaller gage. In using such wire, it is necessary to remove the insulation from portions of the coated wire in order to make electrical connections with wire terminals, etc. Removal of the insulation from wires, and. especially from wires of small gage, has long presented a problem the successful solution of which has increased in difilculty as the demand. has arisen for wires of smaller and smaller gage until even the insulated Wires are of such small diameter that they can hardly be seen with the naked eye. Wire of 0.0009 inch diameter uninsulated, having applied thereto an insulating covering or coatin 0.00015 inch thick, giving a total coated wire diameter of 0.0012 inch, has not been uncommon for some time past, particularly where the wire is provided with an adherent insulating coating. The smaller the diameter of the insulated wire, the more difficult it has been to strip the insulation therefrom.

It-has been proposed to remove the insulation from portions of such insulated wire by various means and I'methods, as by manual scraping or abrading, by abradingby machine (as, for example, by the periphery of a rotating wire brush), by burning, by dipping in hot solder, by the use of chemicals, etc., but all such known means have .met with little practical success, particularly with Wires 0.003 inch or less in diameter, due to some one or more of such causes as undue cost, undue time and labor required, a substantial. reduction .in the often critical diameter. of V the metal wire which impairs or destroys its usefulness, mechanical or chemical ers cleaning the wire, and others.

the injuries to the wire do not result in wire 2, injury. to the stripped portion of the wire, rupture of the Wire by burning or by stripping tools, failure to clean all of the coating from the stripped portion of the wire, hazards to'work- Frequently,

rupture until after the device in which the wire is employed has been manufactured and put" into use. Other such injuries result in great ping the wire or during manufacture of articles in which the wire is used. Production of articles including such wire as an element thereofhas been excessively slow due to time re-' quired to strip wire and'to the high percentage of'stn'pped wire rejected as unfit for use. Much consideration has long been given without success to ways andmeans of avoiding the hazards to operatives in stripping. the wire, the great economic waste existent in manufacture of ar-' ticles requirin such wire, and the serious consequences resulting from wire failure in use of such manufactured articles.

The general purpose of the present invention is to provide an improved means for rapidly, safely and'economically stripping or removing insulating coverings and coatings cleanly and entirely from a desired length of insulated wire,

including particularly insulated wire of a total diameter of 0.003 inch, or less, Without injuriously affecting or weakening the metal wire or substantially reducing the diameter of the metal wire.

Av further. purpose of the invention is to provide an improved'apparatus whereby insulation is stripped by mechanical means from such wire cleanly and with great rapidity without adversely affecting the metal Wire and with little or no liability of injurious effects on the operative.

A further purpose ofthe invention is to provide a safe, simple, inexpensive and effective an paratus in which the insulation is stripped or abraded from such wires by a novel rotating brush with brushing elements, bristles, or filamerits of which extend axially of the brush to an'annular workin end face ofthe brush and are glass fibers or filaments of the kind-known as continuous fibers or filaments as distinguished from the relatively short glass fibers knownas staple fibers.

A further purpose of the invention is to provide a platen means so constructed and so associatedwith such a'brush as is'above described as" to enable the brush to act with great efil.

3 ciency on an insulated wire in a manner to obtain the ends desired.

Other purposes and advantages of the invention will appear from the following description of those illustrative embodiments thereof shown in the accompanying drawings.

In the drawings,

Figure 1 is a perspective view of a. wire stripping machine constructed according to the invention;

Figure 2 is an exploded detail perspective view illustrating certain parts of the machine;

Figure 3 is a fragmentary vertical sectional View of the machine taken on the same plane as Figure Figure 4 is a detail perspective view showing the machine equipped with a modified form of platen or counter-pressure plate;

Figure 5 is a detail sectional view on line 5-5 of Figure 6;

Figure 6 is a, detail end view of parts of the machine illustrating also how a wire is introduced for stripping;

Figures '7 and 8 are detail views similar respectively to Figures 5 and 6 but illustrating the machine equipped with the modified platen or counter-pressure plate shown in Figure 4;

Figure 9 is a diagrammatic top plan or top edge view illustrating more clearly certain details common to both forms of platen or pressure plate; and

Figure 10 is a detail horizontal sectional view taken on the horizontal plane in which lies the axis of adjusting screw 31.

The improved machine has a rigid framework II] adapted to be seated upon a table or work bench. A horizontal shaft I I is journaled in suitable bearings in framework Ill and has fixed thereon at one end thereof a, three-step stepped pulley I2. An electric motor I3 is mounted on the framework with the motor shaft I4 parallel to shaft II. A three-step stepped pulley I5 is fixed on one end of motor shaft I4 opposite pulley I2 and is connected with pulley I2 by a drive belt I6, the pulleys being reversely stepped relatively to each other, as shown, so as to provide in known manner for three changes of speed of drive of shaft I I by motor I3. Current is supplied to and cut ofi from the motor through the medium of a suitable electric switch having an operating handle I! readily accessible to a user of the machine. Mounted on shaft I I to rotate therewith, and located at the opposite end of said shaft from pulley I2, is a wire stripping brush or tool designated generally by the reference numeral I8.

The brush I8 is of novel construction and is mounted on shaft II in a novel manner as now will be described. The brush shown comprises a cylindrical body or band I9 of closely compacted fiber glass filaments which constitute the brushing elements or bristles of the brush. These filaments are flexible and abrasive and are of the kind known as continuous fibers and all extend longitudinally of and parallel to, or substantially so, the axis of the band of filaments. Preferably, the filaments of the band I9 are flexibly bonded or cemented to each other throughout the body of said band by an elastic cement binder. At its inner end, the flexible band IQ of bonded glass filaments is bound on the exterior of a narrow annular metal ferrule or ring '20 having at one end thereof an outwardly extending flange 20a, abutted by the inner end of the band of filaments. Each filament extends from end to end of the band of filaments and said band of filaments projects from the ferrule 20 throughout the major portion of the length of the band and is bound at the inner end of the band on the ferrule 2820a by means of a wire 2! wrapped helically about the exterior of the band at the inner end of the band with the ends of the wire secured in any suitable manner as, for example, by twisting or tying the wire ends together. The ferrule 2il2Ila, the band of filaments I9, and the bandbinding wire 2i constitute a replaceable and axially adjustable unit or re-fill unit of the brush I8, as hereinafter pointed out.

An internally threaded collar 22, having a knurled periphery, is provided with a reduced annular portion 22a to receive the flanged ferrule 202iia, the length of portion 22a corresponding to that of the ferrule. Collar 22 is screwed on an externally threaded intermediate portion of a sleeve '23 for adjustment along the sleeve. Sleeve 23 closely embraces shaft I I and is formed at its outer end with an enlarged annular head 23a of greater internal diameter than the diameter of the main shaft-embracing bore of the sleeve. The external diameter of the head 23a corresponds with that of ferrule 20, and this head serves as a rigid internal support for the band of brushing elements of filaments. The outer or working end of the band of brushing elements projects slightly beyond the outer end of the head 23a of sleeve 23 in the assembled condition of the brush and machine, the extent of this projection or protrusion preferably being about to inch. I'he inner end of sleeve 23 is notched at 24 at two diametrically opposed points to closely embrace the protruding ends of a pin 25 driven through a diametrical bore 26 in shaft I I to thereby provide a positive driving connection between shaft II and brush I8.

The brush supporting end of shaft I I is formed with a reduced and externally threaded terminal portion Ila. to receive a clamping washer 21 and clamping nut 28 which releasably hold the sleeve 2323a on shaft II with the inner end of the sleeve abutting a collar I Ib fixed on the shaft. The band of brushing elements is clamped tightly to the enlarged head 23a of sleeve 23 by a divided metallic clamping band 29 of known form, the three sections of which are connected by nut and bolt band contracting means 30 in known manner to releasably but tightly grip the band I9 to the periphery of annular head 23a, to rotate with sleeve 23 and shaft II. The outer edge of band 29 is preferably in the same plane as the outer end of head 23a, and the outer end of the band of filaments I9 projectsslightly beyond the clamping band 29, preferably and 3 inch. The band of filaments may be advanced beyond the outer end of head 23a, as the filaments wear away in use, by screwing collar 22-220, toward head 23a of sleeve 23. It will be observed that the brushing elements or filaments of brush I8 project at their working ends only a very short distance (1 5 to inch, preferably) outward from between head 23a and clamping band 29, so that only a very short length of each filament at the working end of the brush is flexible during brushing action. The threaded terminal portion IIa of shaft II, and also the washer 2'! and nut 28,

. are housed within head 230. which projects outelemeritsor filaments 'o'fthe"hollow cylindrical handle of filaments. Opposed 'to thew'orking endface of 'this 'brushis-a small and substantially non-rotative flat platen orcounter' pre'ssure plate which'is 'sosupporte'dthatit is capable 6f limited universal tilting movement aboutanfaxisparallel to'th'e brus'h'aXis "and may move against yielding resistance away from the working end face of the brush. "Two forms of platens,namely"" platens -3I arid' 32,are shown'irrtl'ie drawings, each platen being airigid rectangular'plate and having rigid "therewith a pendent arm which is "engaged with apart "of "the machine to prevent anysub- 'staritial rotation of the platen. Each lplaten proper, apart fromits pendent arm, "is 'off'such size and shape tha't it extends across a lifni'ted arc of the end face of the annular bando'f brushing elemen'tsof the brush, said are not exeeeding'l80degrees and-ipreferablybeing of about GO'degiees. Eitherform of platen mayibeused, and the machine shown islprovided with means forsupporting each form of platen. In Figures 1, 3,5, and' 6, one'form of platen'is'shown mounted in the machine," and inFigures 4, 7 and 8, another form of platen is shown mounted in the machine. -l -igure 9 shows onan enlarged scale features of construction 'co-m'mcn-toboth-forms of'platen. I I

The p'latenmounting means now will be described after which will *be described the --con- -struction of-each of the twoalternatively usable 'platens 3i" and 32 and the manner in-which-each platen is supported by the platenmounting means. i

Extending across the vertical plane in which liesthe common axes'ofshaft l -land' brush "I8 is e; horizontal *armtfi which is- -journaled atone "endthereofpn a vertical pivott l. Pivot "3-4 is *iixedtoimmeworklt at one' side of said vertical "plane and said arm 33' is-locatedat a lower level 'thanthe brush l8' and'is partly overhung by'the outer'or worliingend=ofthe-brush. At the oppositeside or saidplane the'other end' of said 'arm is formedwi-th a yoke 35 in which is-journaled theends of-"a shortverticalshaftbr pintle 3B. A thumb screwdl "has a shank-extending through a'h'orizontal' bore in s'haittfifsaid shank having a "screw threaded "terminal portion Sla variably screw able into a horizontalaiid' screw-threaded "boreun'a vertical "post'or stud 38 fixed to' frame- "work Ill, said bore'in post 38 extending parallel to, or substantially paralleltoyshaft H. The shank of -scre'w1l,whichis "not threadedwhere it'p'asse'sthrough shaft 3'63is enlarged adjacent thehead of'screw 31 to "provide a shouldertl'b which "abuts shaft *3t. An expansion spring 39 iscoi'ledaboutthe'shank*ofthe thumb screw and abuts shafttb'an'd post "3'3'to constantly urge the "adjacent end of arrn"'33awayfrorn post 38 as'far "aspermitted'by-the" threaded adjustment of the 'screw'in post .38. '"Thethre'adsof the screw 31 "and of'theboreinthe post38 are of fine or .mi- 'crometricipitch. Micrdmetric swinging adjustment of arm "33 may be made by turning the thumbscrew', the parts'being so constructed and arranged that the short maximum range of swinging adjustment of thearm carries the axis of shafttt equal distances to opposite sides of a vertical plane normal "to the vertical plane'in which 'lies the common axes of shaft H and brush l8 and passing through pivott l.

In,-ior.substaritially in, the vertical plane of the common axes of shaft 1 I and-brush l8 is an up- 'standing. post or bar '40 which-is .of non-circular cross-section and is rigidlyheld at'itslower end 6 toarm 3'3 for adjustment ofpostfiil -toward"and from the working end of the brush substantially insaid vertical plane by adjustmentof arm 33 through the medium of thumb screw "31. -Arm 33 has"agpost-receivingbore of substantially the same cross-section as 'the'post as "hereinafter described. The-post in extends-upward from arm 33 at least substantially entirely past the outer or working end face of brush l8, as shown. At the 'si'dethereof farthest from'brush [8, the post M is provided with a medial longitudinal groove ll extending throughout the length of the post, and saidp'ost has a medial slot 42 extending across its upper end, said groove and slot conmeeting with each other and lying in, or substantially in, the vertical plane of the common axes of shaft ll and'brush [8 in all adjusted positions of arm 33.

'To. directly support the platen 3l,'or the'platen t2, the machine is provided'with a platen support or hanger which is resiliently flexible. This 'hanger comprises a piece of resilient metal wire having a longlegdtseated looselyin groove "4! in post llhand also having a short horizontal'leg M extending from the upper'end of'leg43 loosely through slotll'i'in post iil beyond thelinner edge of post it and toward brush It, said leg "44 extending parallel, or substantially so, to thebru'sh axis. Thefplaten hanger A3 44 is adjustable up and down relativelytopost Ml and is clampedin adjusted position by a thumb screw 45 which is threaded through arm33 to 'abut'the long leg 43 of the hanger adjacent the lower end of the hanger, and-post. The leg' i3 of the -hanger is preferably slightly shorter than 'the distanoebetween the lower end of slot 32 and the lower end of post 58.

For convenience in manufacture, the arm '33 is provided with a passage of substantially fthe same cross-section as post til to'receive the lower ends of post iil land of hanger lt i-'4, the ,post being, as shown, of substantially rectangular cross-section and the arm andposthaving'flat lower faces adapted'to wipe over an underlying flat surface of the main frame when the arm is adjusted. The depth of slot 62 in post 4!! is such that the platen hanger may be adjusted to position the tip of the conically tapered end Ma of leg 44 of the hanger opposite the end face of the annular band of brushing elements above the brushwaxis (i. .e. between prolongations of the inner and outer peripheries of bandit and above said axis), or at a point which is above the brush axis but inside a prolongation of the inner periphery of band it] of brushing elements. When the thumb screw 45 is screwed inward, itserves .to lock the post Ml to arm 33 and also to lock hanger l3 l in its adjusted relation to the post ii]. The post it could, of course, be made integral with arm 33, if desired.

To vary the force necessary to flex the upper end of thehanger lt-Harvey from the working end face of brush 18, there is provided a collar or sleeve lliwhich embraces, and is slidable up and down relatively to, the post ii] and hanger leg 43, and which has threaded therethrough a set screw ll adapted towbind leg 43 to post 40 at varying points along the length of said hanger leg. To prevent frictional binding of the hanger 33-54 in groove 4i and slot 42, the groove and slot are made wide enough to provide slight side clearance for thehanger, as indicated particularly in Figures 6 and 8.

- Platen 3| has a straight pendent arm ig rigid therewith and lying in the same plane as the platen proper, said arm having a longitudinal slot50 in its lower end portion through which extends, when said platen is mounted on the hanger, the horizontal crossbar of a wire yoke The yoke 5| is rigidly held to arm 33 with its crossbar parallel to shaft II and lying in, or substantially in, the vertical plane in which lies the common axes of shaft II and brush 18, said crossbar extending partly under, and also partly outward beyond, brush 18, as shown. Slot 50 is slightly wider than the yoke crossbar, and'the crossbar extends through slot 50 intermediate the ends of the slot, to prevent binding of the arm 49 on the yoke when the platen is tilted on the conical end 44a of the hanger. The connection between the arm 49 and yoke 5i prevents any substantial rotation of the platen 3i when the brush i8 is rotated.

The pendent arm 52 of platen 32 is shorter than arm 49 of platen 3| and is inclined downward and outward for engagement of the lower end of said arm 52 in a longitudinal slot 53 in post 40 when the platen 32 is'mounted on the hanger 43--44. Slot 53 extends medially of post 40 and is slightly wider than the arm 52 and is of sufficient depth to permit limited facewise tilting of the platen 32 into and out of a vertical plane normal to the vertical plane in which lies the axis of the shaft II. The above described arrangement permits limited universal tilting of platen 32 on the conical hanger end 44a without binding of platen arm '52 on the post 40, and prevents also any substantial rotation of the platen when the brush is rotated.

The pendent arm of each platen is a rigid arm which is connected with the platen midway the vertical or side edges of the platen and preferably is formed integrally with the platen, as shown. Each platen has an accurately ground planar inner or working or wire-engaging surface or face which is connected with the outer face of the platen at the two vertical or side edges of the platen by two flaring side edge surfaces 54, best shown in Figure 9, which gradually merge with the planar inner or working surface of the platen. Preferably the flaring side edge surfaces of the respective platens are curvilinear surfaces of large radius.

The dimensions of the alternatively usable platens 3| and 32 are such that, when either platen is mounted on the hanger, the annular working end face of the brush is always opposed to the planar working surface of the platen in a single fixed arcuate zone which does not exceed 180 degrees of said brush face. This is an important feature. In the constructions shown, this zone is located above the horizontal level of the brush axis and crosses the platen from one vertical side edge to the other of the platen between and short of the upper and lower edges of the platen.

In using platen 3!, the platen hanger is preferably so adjusted that the conical tip 44a of the hanger is directly over, or substantially directly over, the brush axis with said tip slightly below a prolongation of the inner periphery of the band of brushing elements l9, as shown in Figures 1, 3, 5, and 6. In using platen 32, the platen hanger is preferably so adjusted that said hanger arm tip 44a is opposed directly to the annular working end face of said band of brushing elements and is directly over, or substantially directly over, the brush axis, as shown in Figures 4, 7 and 8. When either platen is mounted in the machine, the arm 33 is so adjusted by screw 3! that the planar working surface of the platen either only very lightly contacts the working end face of the'brush without any fiexure of the resilient wire hanger 4344, or else so that there is a minutenormal clearance between the brush and platen not exceeding the diameter of the metal core of the coated wire to be stripped. Such adjustments of the platen will insure proper insulation stripping action and also prevent undue wear of both the brush and the platen.

When the brushing elements of the brush 18 are worn away as far as practicable, the ferrule 20-4011 and the band IQ of brushing elements bound thereon by wire 2|, are removed and a refill comprises a new ferrule and a new band of brushing elements bound thereon by a new binding wire 2| is incorporated in the brush.

When the band of brushing elements is to be adjusted to compensate for wear, by screwing the ring 22-22a toward head 23a of the brush core or sleeve 23, the clamping band 2930 should be loosened so that the re-fill unit can move axially relatively to the sleeve 2323a.

Mode of stripping a wire In the drawings, the brush is shown as being continuously rotatively driven by the motor in counter-clockwise direction as indicated by the arrows in Figures 1, 4 and 6, during use of the machine. With this direction of brushrotation, the mode of stripping the insulation film from a desired length of an insulated wire is as now will be described.

The insulated wire '55 (Figure 6) is grasped between the thumb and index finger of a hand of an operative and is introduced laterally thereof between the brush and platen as indicated in full lines in Figure 6, and the operatives hand then is moved directly, or substantially directly, downward, as indicated in dotted lines in Figure 6, this downward hand motion being continued until the wire is carried below the platen proper, i. e. below the rectangular plate 3| or plate 32, whichever one is mounted in the machine. As the wire is introduced, adjacent the point of finger grip thereon, between the end faceof the brush and the adjacent flared vertical side edge surface 54 of the platen plate, it will be gripped with progressively increasing frictional force between said brush face and platen side edge surface and thereafter carried by the rotating brush between the. brush end face and the main or planar working surface or face of the platen adjacent the upper right hand corner (as viewed in Figure 6) of the platen. As the operatives hand moves down and the brush rotates, the wire is drawn on down past the platen by the action thereon of the rotating brush and the brush abrades the insulation from that length of the wire which passes between the planar inner face of the platenand the end face of the brush. In passing between the platen and brush, the wire to the left (as viewed in Figure 6) of the point of finger grip is rolled or twisted through one or more revolutions, the extent of roll or twist progressively increasing to the left of said point of grip.

After a length of the wire has been carried down past the platen proper, it is no longer gripped between the brush and platen and may be withdrawn endwise and the same length thereof again passed down between the platen and brush as above described, if the insulation has not been entirely stripped from said length of Wire by the smglepass. Preferably, where more. than one p assisrequired to strip the insulation, the, wireis repeatedly passed between he brush-end p a n b m vin th w re rippi and. of," the operative alternately down and up to pass saidlength of thewire down andup betWeenthe brush andplaten as often-as may be necessary to clean, the insulation from the wire.

The universally tiltable platen will-tilt to facili tateandease the initialgrip of the wire between the, brushandplaten on each hand strokeandtheplaten hangerwill'resiliently flex away from thebrush to permit the wire to, be easily drawn by the rotating brush entirely pastthe platen with very little resistance butwith, enough resistance to keep the wire lightly .pressed by the platen against the brush end face.

The rotar mOiJiQI f thev brush, end face past the nonrotatin platen carries the wire down past If an end portion of a wire is to be stripped, the

wire 'i introduced as shown inEigureG so that thedesired end of. thewirewill.hasstbetween the brush and, platen. If an intermediate portion of a. wire. is to be stripped, such, intermediate portion is passed between; the. brush. and platen. Where a longlength of wire is to be stripped, successive lengths, thereof may be stripped by passing such lengths once or more between. the brush. and platen. The down and up passes, above described, of the wire being stripped ob= viously will result in the wire being. twisted on the. clown pass dcorrespondingly untwisted onthe up p ass, w ich. is advantageous where mere than .116 passisrequired to;- fi lly. clean their;- sulation from the wire since the wire at. the end oifyeach upward pass. is restqred toits untwisted ondit on.

The apparatu and method above describediare efiective; to clean-ly and entirely strip the insular ticn froma desired length or wire of the class described without hazard t the operative and without either reducing the, metal cone of the coated wire, rupturing the wire or producing nich s, or cavities. inthe-metal'. cpre or wireprope f,

nor-is, the Wire subject to such injuries, as. are or maybe produced; by burning oil, the insulation, or. a by em r na e ins a ion. b chemical s lvents. The brushing unit tiltof; thebrush com prising the glass filaments. and their binding agent, is also ofsuch] construction. and materials that particles thereof and particles of the removed coating do not adhere to. themel ql Wire core but, rather, adhere to each. other and fall away from the wire. Y

Since, even with brushes. of. the form shown, there is. a. tendency-of the, brushing elements to acquire, a, perm nent bend in one direction if the brush s alwaysrotat d i nedire t n the motor [3 preferably is of the known reversible drive type and thecontrol switch L1 is of the W yp fiectire o uto urren f said m tor. r teenereize d m tor.- tq. rotate s-sh t in We dime gn rthe other'es may be desired. When the direction of rotation of the brush is in reverse to" that indieated in Figure (6;

the operativefs band would bep os itio ned and; movedat the left of-the brush as the latter isshQWn in Figure 6.

The ideal speed ofthe-rotationof the brush; shaftdependsupon the nature of the insulating covering or insulating coating to be removed.

It has been found thatby ueing the best of three speeds of rotation of the brush, all types of coatings can be stripped to best advantage, and this is the reason why the three-speedpulley and{ belt drive shown is provided, although change be speed is not essential to the practice of thein vention with different types of coating. Thevariable pressure required to make the platen mount yield is also a 'desir able-featugewith ferent types of coatings or' coverings; but this variable pressure yield isnot essential noris-any; yield of the platen mount essential, although the yield variable, or otherwise, is highlydesirable. Where a yielding platen mount such as shownis employed," the pressure should; always; be very light. The idealQr best R; P. M, and plateri'yi'eld resistances are determined largely by the nature of the insulation in accordanee with l fnownprep tice in the grinding art WhereintheRI'P'. oi the tool and pressure ofthe tool on the wgrk aredesirably varied in accordance with the phyic wai s t me It s ot s emalwaim kin a of the platen beaboye the horizontal level of'the brush exist t is note sentiel he? h.. x e. horiz n elt s. net es enti l al ho gh. g ly d i a e e a ti al.pur pse fihat. he p aten be. eit er. unable r. ieldeb e. t. me te t that .theworking fa ce o f the, brush be in a plane inter ct neend nprma io e ru h. flexible. har cter. Q he r i eend ete fth br sh. nd h eclieceat d ner encfihe ylindrieal ody 9. adant he bnshtaect eifieienilr to. .ri suletic irqm. e. re en ire y. argue he. h iltable. n the. re ease. m unt Q h.l? @ll .i fi 2 19 1 and. b th. ble e ea y w r i trod c icn prereeiiqn. of. e 1 9: ture, for good cleaning or the W118. (1- t ll: urine ont nuous me ed o length. iwire wi azoh f he bru h ac d rine e. as? f the. win t ro shse d. an nd. I9 nab n clean.- m f. wireswithine eiv n ma reused diam: eters withoutadlustm ll 0f, helaten. meant.

Desirablythe cylindrical body L9 qf fleggibleand honde m i uousfibe essfilements ni lered as a part of the bradi lg dql 9. brush. may b formed by producing a sleb of gmpactedfand bonded fibers with the fibers all'runn g npne di c ion. and. fr m nd m nd. Qf the lab i lowin i produc ng th s slab. th ash n s. i ROesch Unite statesr tentb a mi lin ss ed ugust 6, 1940. While. an Qtthejfibsr andin agents mentioned in said patent may be nsed, it is preferred that an elastic bondlngjagent such as er ement. or he, rubber r rubbe 9. pound bondi g a nts u h a wer m ntioned in said patent be employed; After forming the slab, it is severed at intervals, at right angles to the direction of' run of thefibers, into lengths corresponding to the desired length of the tool body l9. From these lengths arecut segments of the cylindrical tgol body, in which segments substantially all of the fibers extend longitudinally of, and from end to end of, the segments. The required number of segments is assembled to form a cylindricalbody, the abutting .cherecte cistis ,Qi he.mater elfiiwl hthe.

. .11 faces of the segments of which are bonded with some of the'fiber bonding material. The cylindrical body is bound on a ferrule Elk-a by a wire 2|, and the working end face of the body is-ground until it is normal to the axis of the Machines of the kind shown and described have proven particularly successful in removing insulation from wires of even such small diameters as 0.003 inch and less. One such machine used to strip insulated wires of diameters of 0.003 or less inch was operated under the following specificconditions and had the following specific features of construction:

Filament band I9 had an external diameter of 2.25 inches and an internal diameter of 1.75 inches; the fiber glass-filaments were of diameters ranging from 0.0006 to 0.0008 inch; and the bonding-material for the filaments was a neoprene water dispersion. I

-The platenmeasured (exclusive of its pendent arm) 1.00. inch wide and 0.75 inch high. The working face'of the platen opposed theworking end face of the filament band through an arc of about 60 degrees.

The three-speed drive was arranged to drive the brush at either-900 R. P. M., 1200 R. P. M.

or 2000 R. P. M. r

. In stripping ordinary enamel magnet wire long known in commerce and with diameters of from 0.0008 to 0.004 inch, the platen mounting means was-adjusted to permit the platen to yield against minimum or substantiallyzero resistance so that the platen exerted practically no pressure on the wire. For such ordinary enamel wires having diameters within the range of 0.0008 to 0.0015 inch, the brush was driven at 900 R. P. M., while with such wires having diameters from 0.0015 to 0.004 inch, the brush was driven at 1200 R. P. M.

In stripping magnet wires of diameters of from 0.001 to 0.003 inch, insulated with either Formex or Formvar, the brush was driven at 2000 R. P. M. and the platen mounting means was adjusted to exert a somewhat greater pressure on the wire than the minimum or substantially zero pressureabove mentioned, but still to exert only slight pressure. I Although we have thus described-our invention in considerable detail in the best forms of which we, are aware, in accordance with the patent statutes, it will be evident that various changes and modifications may be madeby those skilled in the art without departing from the spirit of our invention. Accordingly, we desire tobe limited only by the prior art and the scope of the appended'claims.

We claim:

,1. An apparatus for the purpose set forth comprising, in combination. a rotatively mounted tool having encircling its axis a cylindrical body of abrasive filaments arranged with the filaments extending longitudinally of the body and forming at one end of the toolan annular abrasive and flexible working end face of the tool normally lying in a planenormal to the tool axis, means for rotating the tool, a platen having a planar working surface opposed. to said working end face of the tool through an are not exceeding 180 degrees, and means to restrain the platen from substantial rotation about the tool axis and to support said platen for the passage of a length of insulated wire laterally of the wire between and in contact with said platen surface and said toolface for stripping of imll ltion from the wire by said tool face.

, 2. An apparatus, as claimed in claim 1," having means for micr'ometrically adjusting the platen bodily toward and from the working end face of the tool into and out of contact with.

the working end face of the tool.

3. An apparatus, as claimed in claim 1, where-- in the abrasive filaments of the tool are fiber glass filaments of the continuous type, and. wherein said tool includes means engaged with said body of filaments immediately adjacent said working end face of the tool to hold said body of filaments against flexure and to leave free to fiex a short end portion of said body which terminates at said face.

4. An apparatus, as claimed in claim 1, where,- in the abrasive filaments of the tool are flexibly bonded throughout the cylindrical body of filae ments by an elastic cement binder, and said body of filaments is held at its inner and outer surfaces immediately adjacent its working end face against flexure. v

5. An apparatus, as claimed in claim 1, having means supporting the platen for limited universal tilting movement thereof relatively to the tool out of a position in which the working face of the platen is parallel to the plane of the working end face of the tool. I

6. An apparatus, as claimed in claim 1, having means yieldingly urging the platen facewise toward the Working end face of the tool, and means to positivelylimit such movement of the platen.

'7. An apparatus, as claimed in claim 1, wherein the tool includes a rotatively mounted rigid core encircled by said body of filaments, and means for adjusting said body of filaments axially on thecore to maintain the working end of said body of filaments projected beyond one end of the core as the body of filaments wears away in use.

8. An apparatus for the purpose described comprising, in combination, a tool mounted for rotation about a fixed axis, said tool having a flexible cylindrical abrasive body which encircles the tool axis and terminates in an annular Working endface lying in a plane normal to said. axisfthe tool further having means gripping said body internally and externally of the body entirely around the body in a zone closely adjacent but spaced from said end face of the body and holding the gripped portion of the body against flexure and leaving said end face and a short length of said body from said face free to flex, means to rotate the tool, arigid platen having a planar surface adapted to extend over said end face of the tool body through an arc not exceeding degrees, and platen supporting means to hold said platen against rotation with its said surface opposed to said end face of the tool body for passage of a wire laterally thereof between and in contact with said platen surface and tool body end face to strip the wire.

9. An apparatus, as claimed in claim 8, wherein the tool rotating means is adapted to rotate the tool at different selected speeds, and the platen supporting means is constructed to permit the platen to move away from the end face of the tool body against yielding resistance and includes provision for varying said yielding resistance.

10. A rotary abrasive tool, for stripping insulation from insulated electrical wire, comprising a cylindrical body of closely compacted flexible glass filaments substantially all of which ex- 13 tend from end to end of the body substantial] longitudinally of the body, a rigid core extending axially into said body and terminating short of one end of said body, said core having a cylindrical peripheral surface supporting said body adjacent said one end of the body, said body having at said one end a working end face lying in a plane normal to the tool axis, and means releasably clamping said body entirely thereabout to said core to rotate with said core with a short cylindrical portion of said body free of said clamping means and core and extending to said end face of the body.

11. A rotary abrasive tool, as claimed in claim 10, wherein the glass filaments are flexibly bonded to each other throughout said body by an elastic cement.

12. In an apparatus for removing an insulating coating from a coated electrical wire, the combination of a platen having a rigid and planar working face for contact with a length of a coated electrical wire from which the coating is to be removed, a coating-removing tool having an annular working end face which is abrasive and universally flexible and normally is disposed in a plane, means to support the tool for rotation about a fixed axis with the working end face of said tool opposed to and crossing said working face of the platen through an arc not exceeding 180 degrees, means to support the platen against substantial movement about the axis of rotation of the tool and in 14 position for lateral passage between and in contact with said tool face and platen face of a length of wire from which coating is to be removed by the tool, and means to rotate the tool about said axis relatively to the platen.

'13. An apparatus, as claimed in claim 12, having platen supporting means adjustable to selectively position the platen with its working face in and out of contact with the working face of the tool, said adjustable supporting means supportingthe platen for limited universal tilting of the platen relatively to said means.

14. An apparatus, as claimed in claim 12, having platen supporting means yieldingly supporting the platen for movement away from the Working face of the tool, and means for at will varying the resistance to such yielding move ment of the platen.

LOUIS M. CARPENTER. RUDDLPH G. ROE'SCH.

REFERENCES CETED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 162,390 Joyce Apr. 20, 1875 1,005,924 Baldwin et a1. Oct. 17, 1911 1,086,743 Abbott Feb. 10, 1914 1,424,482 Jannell Aug. 1, 1922 2,018,648 Dinley Oct. 22, 1935 

